Regulators: ab3100 - fix probe and remove annotations

Probe and remove methods should not be marked as __init/__exit but
rather __devinit/__devexit so that the needed sections stay in memory
in presence of CONFIG_HOTPLUG. This is needed even on non hotpluggable
buses.

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>